The term ‘air gap insulated manifold’ is used to describe air gap insulated manifolds having an inner shell and an outer shell, which can be installed individually as a separate component. Such a separate air gap insulated manifold is always only assigned to an outlet opening on the engine side and does not form a collecting manifold, which combines a plurality of outlet openings on the engine side.
Air gap insulated manifolds which are connected in flow direction to the housing formed as a collecting manifold are described as inner air gap insulated manifolds. Those air gap insulated manifolds which are connected to the respective inner air gap insulated manifolds in the flow direction, are described as outer gap insulated manifolds.
Inlet opening, outlet opening or connection opening are to be understood as the respective end of the pipes or a housing which is connected by further connection means, such as flanges or welded material, to another pipe or housing leading further away.
A housing for an internal combustion engine configured as a collecting manifold with a plurality of exhaust gas conduits is already known from EP 1 914 401 A2, one end of which having an exhaust gas inlet opening can be connected to an outlet of the internal combustion engine and the other end of which is connected to a collecting device having an exhaust gas outlet opening. A first exhaust gas conduit is formed as a casting from the outlet of the internal combustion engine to the collecting device. On both sides of this collecting device a further collecting manifold is connected, by means of which two outlets of the internal combustion engine are brought together. The two collecting manifolds are configured as air gap insulated manifolds.
An identical design of the exhaust gas conduit with a total of three collecting manifolds is described in DE 101 44 015 A1, in which the central part is formed as a double-walled, air gap insulated collecting housing made of sheet metal.
DE 39 25 802 A1 describes a casting for the connection of six outlets of an internal combustion engine to an exhaust gas system, serving as an adapter for six manifold pipes.
According to DE 103 01 395 A1, a double-walled housing configured as a collecting manifold is known, in which four connection openings are provided for the four outlets of the internal combustion engine.
DE 10 2011 106 242 A1 describes a system made of individual manifolds, each of which are inserted into each other in the number of the outlets of the internal combustion engine.
DE 10 2014 103 804 A1 describes both internally and externally identical air gap insulated manifolds.